Rectifier protective system



March 12, 1940. H. WINOGRAD 3,0 3

' RECTIFIER iROTECTIVE SYSTEM Original Filed Feb. 13, 1953 2 Sheets-Sheet 1 RECTIFIER PRQTECTIVE SYSTEM Original Filed Feb: 15, 1953 2 Sheets-Sheet 2 amm/u 6F .4 )4

A65 gyv Patented Mar. 12, 1940 PATENT OFFICE 2,193,083 apor-Irma PROTECTIVE SYSTEM Harold Winograd, Milwaukee, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Original application February 13, 1933, Serial No. 656,524. Divided and this application August 13, 1937, Serial No. 158,843

, 9Claims. This invention relates to improvements in protective systems and more particularly to systems for interrupting the, flow of current in an electron discharge device when one. or more of the electrodes of the device cease to function in the manner which is normal for the connections thereof; and is a division of the ccpen-ding application Serial No. 656,524, filed February 13, 1933, now .Patent'No. 2,123,859, patented July 12,1938. l

In. electron discharge devices provided with a a plurality of electrodes, and operableto function recliners, inverters, frequency'converters, current interrupters, etc one or more of theelece trodes may fail to functionin the manner desired and which is normal for the connections thereof, such failure being possible as a result of one or more of various accidental causes. An anode may fail to carry current because the conditions of vapor pressure and temperature within the space between such anode and the cathode are such that ionization is not sufficiently readily established in such space at the voltage appearing between the anode and the cathode. Such iailures occur particularly easily in electron discharge devices operating in parallel with other converting equipment and also in electron discharge devices in which groups of several electrodes are operat'edin parallel. In devices so connected, the potential of any anode generally becomes positive with respect to the potential of the cathode by an amount which is only slightly greater than the value of the arc drop and which may thereforebe insufficient for ionizing the arc path under unfavorable conditions. When the functioning of the anodes is controlled by the action of control electrodes, the deterioration or failure of one of such control electrodes or a defect in the connection thereof may cause the anode associated with such control electrode to carry current prematurely, tardily or not at all during each normal cycle of operation thereoi depending upon the nature of the deterioration and upon the method of energization of the control electrode. Some of the anodes of the e may also fail to be energized because of ilure of a phase in the source supplying such e or in other apparatus included in the iating current circuit. Such condition may at e, for instance, upon breakage of one of the alternating current conductors or upon failure of one phase of a circuit breaker or as a result of an open connection within the windings offa supply transformer.

fThe operation of an electron discharge device in which only part of the electrodes carry current is highly detrimental to the safety of the I several phase voltages of the device must be increased to obtain the same average output voltas when all electrodes are functioning. In addition, the electrodes preceding and following th inoperative electrode during the normal cycle of operation thereof are even more severely overloaded as they must carry current over the period during which the inoperative electrode is normally functioning. If a group of several electrodes are operated in parallel on one phase of the device, the operative electrodes of the group must carry the current of the'inoperative electrodes in addition to the current normally carried. Such overloads may result in a serious deterioration or even complete destruction of the electrodes, and may also result in the deterioration of the associated transformer windings by overheating. In addition to the detrimental results mentioned, the circuits connected with the device then receive voltage and current components apt to cause interference in communication circuits, train control circuits, etc. by electromagnetic or electrostatic induction.

No indication of the failure of some of the electrodes isgiven by the usual type of ammeter and voltmeter inserted in the input or output circuit of the device as such meters only indicate the average values: of voltages and currents. Such failure could be detected by inserting suitable ammeters in the circuits of each main electrode and control electrode of the device. When the number of electrodes of the device is large, the number of such ammeters becomes large and the installation becomes complicated and excessive in cost. Such ammeters can not be used directly to control or to give an. audible or visible signal or for controlling the disconnection of the device upon failure of one of the electrodes to function because such failure resuits in unequal ammeter readings rather than in any particular value of such readings.

Asimpler, more dependable, and less 8X13E11' sive method consists in utilizing some of the voltage and current components which appear in the circuits associated with the device and in the circuits of any eiectrode-paralleling device associated therewith, upon failure of one or more electrodes to function, such components not beving present when all electrodes carry substan- Another object of the present invention is to provide a protective system for electron discharge devices whereby the flow of current within such a device may be interrupted upon failure of one or more of the electrodes thereof to carry current.

Another object of the present invention is to provide a protective system for electron discharge devices whereby such a device may be disconnected from the supply line or from the output line upon failure of one or more of the electrodes thereof to carry substantially the sameamcunt of current as is carried by other similarly connected electrodes.

Another object of the present invention is to provide a protective system for electron discharge devices whereby such a device may he disconnected from the supply line or from the output line upon failure of one or more of the electrodes thereof to carry substantially the same amount of current as is carried by electrodes connected in parallel therewith.

Another object of the present invention is to provide a protective system for electron discharge devices whereby such a device may be disconnected from the supply line or from the output line in response to the appearance of current or voltage components occurring upon failure of one or more of the electrodes thereof to function in the normal manner.

Another object of the present invention is to provide a protective system for electron discharge devices whereby such a device may be disconnected from the supply line or from the output line, and in which the system is selectively responsive to sustained voltage or current components in a circuit connected with the device when such components are due to accidental or abnormal operation of the device.

Another object of the present invention is to provide a protective system for electron discharge devices whereby such a device may be disconnected from the supply line or from the output line, and in which thesystem is selectively responsive to the flow of sustainedvoltage or current components accidentally appearing in the circuit of an electrode-paralleling device.

Objects and advantages other than .those above set forth will be apparent to those skilled in the art from the following description when read in connection with the accompanying drawings, in which:

Fig. 1 diagrammatically illustrates one embodiment of the invention applied to the control of a six-phase 12-anode electron discharge device operable as an alternating current rectifier, and is designed for the purpose of disconnecting such device from the output line thereof in response to the flow of current in the neutral connection between the secondary windings of two anode paralleling transformers;

Fig. 2 diagrammatically illustrates a portion of another modified embodiment of the present invention applied to the control of a six-phase 18- anode electron discharge device operable as an alternating current rectifier, the protective system operating in response to the appearance of residual current in the connection of the secondary windings of three anode paralleling transformers;

Fig. 3 diagrammatically illustrates a modification of the control circuits of the embodiment illustrated in Fig. 2; and

Fig. 4 illustrates a further modification of the control circuits of the embodiment illustrated in Fig. 2. p

Referring more particularly to the drawings by characters .of reference and considering first the embodiment according to Fig. 1 thereof, reference numeral ll designates a polyphase alternating current line connected with a direct current line l8, I9, through an electric translating system including an electron discharge device 62, preferably of the vapor type, controlling the flow of current therebetween. In the present embodiment the device 62 is shown as having a single cathode H and twelve anodes divided into two groups of six anodes each; and in the description of the present and the following embodiments of the invention, it will be assumed that alternating current received from line H, as the supply line, is to be rectified and supplied to the direct current line l8, l9, as'the output line, but it will be understood that the control elements of each of the herein disclosed embodiments may be utilized for the converse operation, and that such control elements may be utilized for controlling the'operations of electron discharge devices in systems other than alternating current rectifying or direct current inverting systems.

Line II energizes the primary winding 41 of a supply transformer having a secondary winding 48 comprising two groups of star connected phase displaced portions to form neutral points. The phase displaced portions of the two groups of the secondary winding 48 are phase displaced in relation to each other to formasix-phasenetworkand severally connected with an anode M of one of the groups thereof through the phase dispaced portions of the primary winding 63 of a six-phase paralleling transformer having a three-phase star connected secondary winding 64, and through the phase displaced portions of the primary winding 66 of a second six-phase paralleling transformer having a three-phase star connected secondary winding 61. The direct current line l8, I9, is shown as being connected with the cathode I! of device 62 through a circuit breaker I 45 having a trip coil 40 and with the neutral point connections of secondary winding 48 through an interphase transformer 49, as is well known in the art. Such connections through the transformer 49 do not, however, affect the present invention and the neutral points of the winding 48 may, accordingly, be connected with the direct current line l8, I! to the exclusion of the transformer 49.

For the purposes to be hereinafter explained, the neutral point connection of the winding 64 is connected with the neutral point connection of the winding 61 through a signaling device 42 and through the energizing coil of a relay 43; and, as is well known, the division of current between the anodes l4 connected with each portion of the windings '63 and 66 is effected by the flow of three-phase currents between the star connected windings 64 and 61 to the exclusion of the flow of an affective residual circulating current through the signaling device 42 and the energizing coil of the relay 43. If, however, one of the anodes l4 of the device 62 fails to carry current, during a period when current should flow therethrough, the currents circulating between the windings 64 and 61 will no longer be balanced so that a residual current will flow between the neutral point connections of such windings through the signaling device 42 andthrough the 1 energizing coil of relay 43 of such magnitude as to cause their operation.

In the present embodiment, the relay 43 includes contacts 44 arranged to connect a battery 32 with the trip coil 40 of the circuit breaker 45. Upon the occurrence of a failure of any one of the anodes 14 to carry current the residual current circulating through the coil of relay 43 will, therefore, cause the closure of the contacts 44 thereof and thereby cause the circuit breaker 45 to be operated to disconnect the direct current line I8, l9 from the device 62, so that device 62 no longer carries current. As shown the circuit for the trip coil 4b of the circuit breaker 45 includes the contacts of a relay 186 connected across a shunt l0! and energized in response to the flow of current of a predetermined magnitude less than maximum normal load through the device 62. Thus, although the signaling device 42 is caused to operate upon the failure of any one of the anodes l4 to carry current-and thereby indicate such failurethe circuit of the trip coil 40 is not completed and the circuit breaker 45 does not open unless the failure of the flow of current through an anode 14 be such as to result in the overloading of one or more of the anodes 14 remaining in operation. It will be understood also that, in the present embodiment, the relay 43 may be utilized to energize a tripping magnet 3| for controlling the opening of a circuit breaker 21 in the supply circuit of the device 62.

In operation, the apparatus being connected as shown, with the circuit breaker 45 closed, and the winding 41 being energized the anodes l4 connected with each phase portion of winding 48 receive alternating voltages through the paralleling transformer windings 53 and 65, which voltages sequentially render such anodes positive relative to the voltage of cathode ll, causing thereby the flow of current sequentially through each of the phase displaced portions of the windings 48, 53 and 66 and the anodes l4 connected therewith. Due to the action of the transformers 49, ea, 64 and 66, 61, as explained supra, the flow of such current sequentially through each of the phase portions of the winding 48 is caused to flow in equal portions, or other predetermined ratio, through the respective anodes !4 connected therewith for a period equal to substantially onethird of the voltage cycle of the supply line ll.

Should, however, an anode [4, connected withany one of the phase portions of winding 48, fail, for any cause, to carry less than its proportionate share of current, or fail to carry any current, during its normal operating period then the other one of such connected anodes will be forced to carry a current greater than its proportionate share and cause thereby an unbalancing of the currents circulating between windings 64 and 61. As explained supra, upon the occurrence of such an unbalancing of the currents circulating between the windings 64 and 6'! a residual current will flow through the device 42 of such magnitude as to operate device 42, to thereby indicate the failure of an anode [4 to carry current; and of such magnitude as to operate the relay 43.

Should the total load current then flowing through the shunt ill"! be of a value such as not to overload an anode, the operation of the relay 43 would be without effect. Should, however, such total load current be then of such magnitude as to overload an anode l4 the relay 06 will be operated, its contacts closed and the circuit closed therethrough for the trip coil 40, which then operates to open circuit breaker 45 and interrupt the operative connection of the direct current line l8, IS with the device 62 and prevent thereby further flow of current through the device 62.

Thus the system provides, in the transformers 63, t4 and 66, 61, a means for causing the parallel operation of two or more anodes of an electron discharge device; in the device 42 in combination with transformers 63, 64 and 66, 61, a means for indicating the failure of any one of a plurality of such anodes to carry current during its intended periods of operation, and in the relays 43, lot and circuit breaker 45 in combination with the transformers 63, 64' and 66, 61, a means for preventing the flow of current through an electron discharge device, or devices, upon the occurrence of the failure of an anode thereof to carry less than its predetermined proportionate share of current during its intended periods of operation.

In the embodiment illustrated in Fig. 2, winding 48 is assumed to supply current to an electron discharge device 68 provided with eighteen anodes. Each portion of winding 48 is then preferably connected to supply current to three anodes of device 68 which anodes then operate in parallel; the equal division of current between the parallel anodes is obtained by means of three single phase paralleling transformers each having a double primary winding 69, 12, or 14 and a secondary winding H, I3, or 16. During normal operation, the currents in windings H, '13, and it constitute a balanced three phase system of currents so that the three windings may be connectedin parallel with each other to a circuit comprising the coil of relay 43 and signal 42. During such normal operation there will not be any flow of residual current through coil of relay 43 and signal 42. Upon failure of one of the of device 68 to function the currents of windings "H, i3, 76 no longer constitute a. balanced three-phase system of current and a residual current will flow through the coil of relay 43 and signal 42 to give a signal and cause circuit breaker 2'5 to. disconnect winding 12 from line H.

It may be desired not to connect windings H, :3, it in a conductive manner so as to relieve the stress on the insulation between the primary and secondary windings of the several paralleling transformers resulting from such conductive connection. Windings H, 13 and 16 may then be connected with the circuit of the coil of relay 43 and signal 42 over a plurality of current transformers ll, 18 and 19 having their secondaries connected in parallel as shown in Fig. 3.

Relay 43 may also be provided with a plurality of operating coils 84, 85, as shown in Fig. l, which are severally connected with windings I I, l? and It and which act on a single armature 81!. In this manner the relay will close contacts 44 only upon occurrence of an unbalance be'twee the currents flowing in coils 84, 85 and 86. present embodiment, signal 42 is preferably connected in parallel with solenoid 3| and is operated from battery 32 upon closure of contacts 44'.

Although but a few embodiments of the present invention have been illustrated and de scribed, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

In the 1. The combination with direct and alternating current circuits, an electron discharge device comprising a plurality of anodes for transforming current received from one of said circuits and the supply thereof to the other of said circuits, of transformer means interconnecting said circuits and said device in such manner as to cause the flow of current of substantially equal magnitude simultaneously through a plural portion of said anodes, a circuit breaker for interrupting the connection of one of said circuits with said device, means coupled With said transformer means and responsive to unequal flow of current through said plural portion of said anodes for causing the said interrupting operation of said circuit breaker, and means connected with one of said circuits and operable responsive to flow of current below a predetermined magnitude therein for preventing the said operation of said circuit breaker.

2. The combination with an alternating current circuit, a direct current circuit, electron discharge means comprising a plurality of anodes interconnecting said circuits for transforming current supplied thereto from one of said circuits and the supply thereof to the other of said circuits, means included in the connections of said circuits with said electron discharge means for causing the flow of current of substantially equal magnitude simultaneously through a plural portion or" said anodes, and means operable to effect the connection and disconnection of one of said circuits with and from said electron discharge means, of means coupled with the second said means and operable responsive to flow of current of unequal magnitude through said plural portion of said anodes for causing the disconnecting operation of the third said means.

3. The combination with an electric current supply circuit, an electric current load circuit, electron discharge means comprising a plurality of anodes interconnecting said circuits for transforming current supplied thereto from one of the said circuits and the supply thereof to the other of said circuits, means included in the connections of said circuits with said electron discharge means for causing the flow of current of substantially equal magnitude simultaneously through a plural portion of said anodes, and means operable to control the said interconnection of said circuits, of means coupled with said anodes and opcrable responsive to failure of flow of current through one of said plural portion of said anodes during periods of flow of current through another thereof for causing the operation of the third said means.

4. In a control system for electron discharge devices, the combination with a transformer comprising a winding divided into a plurality of phase displaced sections, and electron discharge means comprising a plurality of anodes connected with said winding sections for the flow of current therethrough, of means included in said connections for causing current of substantially equal magnitude to flow simultaneously through a plural portion of said anodes, means for controlling said flow of current, and means operable responsive to unbalanced current flow through said anodes for controlling the third said means.

5. In a control system for electron discharge devices, the combination with a transformer comprising a winding divided into a plurality of phase displaced sections, and electron discharge means comprising a plurality of anodes connected with said winding sections for the flow of current therethrough, of means included in said connections for causing current of substantially equal magnitude to flow simultaneously through a plural portion of said anodes, means for interrupting said flow of current, and means operable responsive to unbalanced current flow through said plural portion of said anodes for controlling the third said means.

6. In a system of the character described, the combination with electron discharge means comprising a plurality of anodes, and transformer means comprising a winding divided into a plurality of phase displaced portions severally connected with separate plural portions of said anodes and forming paths for the flow of current sequentially therethrough, of means included in the connections of said winding portions with said anodes for causing said sequential flow of current simultaneously through the respective anodes of said plural portions thereof, means for controlling said flow of current, and means operable responsive to an unbalanced flow of current through any plural portionof said anodes for controlling the fourth said means.

'7. In a system of the character described, the combination with electron discharge means comprising a plurality of anodes, of means for causing the flow of current of substantially equal magnitude simultaneously through a plural portion of said anodes, means for controlling said flow of current, means operable responsive to an unbalanced flow of current through said plural portion of said anodes for causing the operation of the third said means, and means operable responsive to said unbalanced flow of current when below a predetermined value for preventing the operation of the third said means.

8. In a system. of the character described, the combination with electron discharge means comprising a plurality of anodes, of means for causing the flow of current of substantially equal magnitude through a plural portion of said anodes, means for controlling said flow of current, means operable responsive to the failure of the how of current through any one of said plural portion of said anode during periods of flow of current through another thereof for controlling the operation of the third said means, and means operable responsive to said flow of current above a predetermined value for preventing the operation of the third said means if the value of the said flow of current be less than said predetermined value during the said failure of flow of current through the said one of said anodes.

9. In a system of the character described, the combination with electron discharge means comprising a plurality of anodes, of means for causing the flow of current of substantially equal magnitude simultaneously through a plural portion at least of said anodes, an indicator, means for preventing said flow of current, means operable responsive to the failure of the flow of current through one or more of said plural portion of said anodes during the periods of flow of current through another thereof for causing opera... tion of said indicator and said means for interrupting said flow of current, and means for preventing operation of the said means for interrupting said flow of current during periods of flow of said current at values below a predetermined magnitude.

HAROLD WINOGRAD. 

